Gene expression profiling of neural progenitor populations revealed that Nuclear Factor I (NFI) family genes are specifically expressed in glial progenitors in the developing spinal cord. Preliminary data suggests that NFI genes could be required for the generation of astrocytes in vivo. The goals of this study are to assess whether NFI genes are indeed required for the generation of astrocytes and to elucidate mechanisms that govern the ability of NFI genes to promote astrocytes. To examine whether NFI genes are required for the generation of astrocytes I will utilize both gain-and-loss of function analysis in the embryonic chick spinal cord and I will analyze astrocyte development in NFI mutant mice. Olig2 has been shown to suppress the generation of astrocytes, thus I will assess whether Olig2 can suppress the ability of NFI genes to promote astrocytes using in vitro culture systems and ectopic expression in the embryonic chick. If there is a antagonistic relationship between NFI genes and Olig2 I will investigate whether any biochemical relationship exists between these proteins. Lastly, given that Olig2 can both suppress astrocytes and oligodendrocytes, I will determine whether NFI gene function is epistatic to Olig2 in regard to the suppression of astrocytes and the promotion of oligodendrocytes, or whether NFI can uncouple these roles of Olig2. These experiments will rely on gain-and loss of function analysis in ovo, in vitro, and in mutant mice.